<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        main{
            width: 600px;
            height: 600px;
            border: 1px solid red;
            margin: 50px auto 0;
            display: flex;
            /* flex-direction: column-reverse; */
            /* flex-direction: column; */
            flex-direction: row;
            /* justify-content: flex-start; */
            /* justify-content: flex-end; */
            /* justify-content: center; */
            /* justify-content: space-between; */
            /* justify-content: space-around; */
            justify-content: space-evenly;
        }
        span{
            width: 100px;
            height: 100px;
            line-height: 100px;
            text-align: center;
            background-color: rgb(195, 221, 47);
        }
        /* span:first-of-type{
            margin-left: 50px;
        }
        span:last-of-type{
            margin-right: 100px;
        } */
    </style>
</head>
<body>
    <main>
        <span>1</span>
        <span>2</span>
        <span>3</span>
        <span>4</span>
    </main>
</body>
</html>